The invention relates to a process for the electrolytic polishing of surgical needles and to a device for carrying out this process.
In the manufacture of surgical needles, unfinished needles are produced first with the help of a needle machine. Each of the unfinished needles already has a needle tip, but can still deviate from the final form in the end-region lying opposite the needle tip. For the further production steps in the manufacture of surgical needles, it has proved advisable to arrange a plurality of unfinished needles side by side and, preferably in their end-regions lying opposite the needle tips, secure them to at least one web. Such a web can for example consist of a double layer of paper and/or plastic, the end-regions of the unfinished needles lying opposite the needle tips being glued in between the two layers of the double layer. If several webs are used, two webs arranged parallel to each other can be used for example. The web with the unfinished needles secured to it can be wound up on a reel. The needles can be well stored in this form and are easily managed in further production steps. In order to release the finished or largely completed surgical needles from the webs towards the end of the manufacturing process, the needles can for example be severed or cut off.
In order to improve the surface properties of the unfinished needles, the unfinished needles must be polished at least in the region of the needle tips (i.e. in the region which is used for the completed surgical needles or is essential). This can take place by treating the unfinished needles secured to at least one web in an acid-containing polishing bath which is electrically connected to an electrode. The unfinished needles serve as counter-electrode. The problem is that as a rule the web has no or only a slight electrical conductivity and therefore every unfinished needle has to be brought individually into electrical contact with a counter-electrode. As the web moves with the unfinished needles, breaks in the electrical connection between an unfinished needle and the counter-electrode can easily result, which reduces the quality of the unfinished needle concerned. As a consequence of this, a substantial number of unfinished needles have to be sorted out after the polishing, which can result in substantial costs.
The object of the invention is to provide a process and a device for the electrolytic polishing of surgical needles in which unfinished needles are used which are secured to a web or several webs in the manner described and as a result of which a reliable electrical contact is produced between the individual unfinished needles and a counter-electrode.
This object is achieved by a process for the electrolytic polishing of surgical needles having the features of claim 1 and by a device having the features of claim 18. Advantageous versions are given in the dependent claims.
With the process according to the invention for the electrolytic polishing of surgical needles, a plurality of unfinished needles which are arranged side by side and, preferably in their end-regions lying opposite the needle tips, are secured to at least one web, are moved with the help of the web through an acid-containing polishing bath which is electrically connected to an electrode. The web is guided above the polishing bath. The unfinished needles dip at least with the needle tips into the polishing bath. Above the polishing bath and alongside the web, a metal ribbon connected as a counter-electrode produces an electrical connection with the unfinished needles.
Because the metal ribbon connected as a counter-electrode is a component independent of the web, a good electrical contact with the unfinished needles can be achieved without major expenditure even if the web is an electrical insulator.
The metal ribbon is preferably a continuous ribbon which is guided by means of rolls alongside the web. It is particularly advantageous if the metal ribbon travels at the same speed as the web. To this end, the metal ribbon can be driven separately from the web or alternatively follow passively, in which case it is taken along by friction forces with the unfinished needles moved by means of the web.
In a preferred version, an elastic ribbon located on the side of the web lying opposite the metal ribbon presses the unfinished needles against the metal ribbon. The elastic ribbon is preferably a continuous ribbon which is guided by means of rolls alongside the web and is preferably pressed towards the metal ribbon by means of individually adjustable pressure rolls and preferably travels at the same speed as the web. A particularly good and certain contact between the metal ribbon and the individual unfinished needles is effected by the elastic ribbon.
The unfinished needles preferably enter the polishing bath through a slit-like opening in one end face of a tank containing the polishing bath and leave the polishing bath via a slit-like opening in the opposite end face of the tank. The liquid flowing out of the openings is collected and pumped back into the tank. This configuration has the advantage that the unfinished needles can be moved into the polishing bath without the web having to be raised and then lowered again in order that the needle tips surmount the edge of the tank. A continuous method of operation is made possible, as a result of which the process can be carried out quickly, reliably and at favorable cost. Preferably, at least one of the slit-like openings is arranged in a height-adjustable plate, so that the level of the liquid in the polishing bath can be set by adjusting the height of the plate.
The polishing bath can contain phosphoric acid, sulphuric acid and/or glycolic acid. It preferably contains a mixture of these constituents. A bare metal surface is created in the polishing bath by means of electrolysis, as a result of which the region of the unfinished needles which dips into the polishing bath is polished.
After leaving the polishing bath, the unfinished needles can be rinsed, preferably by being moved through a water bath. Acid residues are removed from the needle surfaces in this way. The unfinished needles are preferably dried after being rinsed, e.g. by being moved through an air flow.
The process for the electrolytic polishing of surgical needles can be carried out completely automatically, the untreated needles being transportable prior to entry into the polishing bath and afterwards with the help of the web. It is particularly advantageous if, at the beginning, the web with the unfinished needles secured to it is provided wound up on a reel and if, when the process is finished, the web with the unfinished needles secured to it, which are polished at this point, is wound up onto a reel again. For this, the at least one web with the unfinished needles secured to it is unwound from a reel prior to the entry of the unfinished needles into the polishing bath, an inter-mediate layer which is preferably located between the turns of the web on the reel preferably being wound up onto a separate reel. The intermediate layer prevents the unfinished needles from chafing against one another and becoming entangled. Accordingly, the at least one web with the polished unfinished needles secured to it can finally be wound up on a reel, an intermediate layer preferably being fed from a second reel, which intermediate layer is wound onto the reel between the individual turns of the web.
The polished unfinished needles can also be monitored by a video camera, e.g. after they have been dried. Defective unfinished needles can easily be severed in the region projecting beyond the web, so that it is not necessary to detach from the web the end-region of the unfinished needle concerned lying opposite the needle tip.